The present invention relates generally to exhaust gas conveyance systems in vehicles. More specifically, the present invention relates to an exhaust gas-cooling device for reducing the temperature of exhaust gases emitted from a vehicle's engine.
Exhaust gas conveyance systems on vehicles frequently emit exhaust gases with extremely high temperatures. The high temperatures can be achieved from routine engine operation, particularly on larger vehicles. Further, the high temperatures can also be achieved during a regeneration event, where collected particulate matter that is trapped in a particulate filter is oxidized. During both routine operation and regeneration events, the vehicle's operating environment can be subjected to undesirable high temperatures.
The conventional method of cooling exhaust gases is an “in-can” or “in-muffler” venturi device. In the path of exhaust gas flow, the venturi device is located downstream of the muffler and upstream of the tailpipe, and uses ambient air to lower the overall temperature of the gases emitted from the tailpipe. In the venturi device, a “cold pipe” draws in ambient air, and sits within a “hot pipe” that forms the path of flow of the exhaust gases. The exhaust gases travel within the hot pipe and around the cold pipe. As the exhaust gases travel around the cold pipe, the exhaust gases are cooled. At an outlet of the cold pipe, the ambient gases and the exhaust gases are mixed in the tailpipe for further cooling. However, new emissions laws require that the exhaust gas temperatures be lowered beyond the capabilities of the conventional in-muffler venturi device.
Thus, there is a need for an improved exhaust gas-cooling device that can adequately reduce the temperature of the exhaust gas to meet increasingly stringent emissions requirements.
There is also a need for an improved exhaust gas-cooling device that can be easily provided on most exhaust gas conveyance systems with little modification to the existing exhaust gas conveyance system.